# std::experimental::observer_ptr<W>::observer_ptr

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< cpp‎ | experimental‎ | observer ptr

constexpr observer_ptr() noexcept; constexpr observer_ptr( nullptr_t ) noexcept; | (1) | (library fundamentals TS v2)
constexpr explicit observer_ptr( element_type* p ) noexcept; | (2) | (library fundamentals TS v2)
template< class W2 > constexpr observer_ptr( observer_ptr<W2> other ) noexcept; | (3) | (library fundamentals TS v2)
observer_ptr( const observer_ptr& other ) = default; | (4) | (library fundamentals TS v2) (implicitly declared)
observer_ptr( observer_ptr&& other ) = default; | (5) | (library fundamentals TS v2) (implicitly declared)

1) Constructs an `observer_ptr` that has no corresponding watched object.
2) Constructs an `observer_ptr` that watches p.
3) Constructs an `observer_ptr` that watches other.get(). This overload participates in overload resolution only if W2* is convertible to element_type*.
4,5) Implicitly declared copy and move constructors. Constructs an `observer_ptr` that watches other.get().

### Parameters

p | - | a pointer to an object to watch
other | - | another `observer_ptr` to copy from

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